U.S. patent application number 10/691311 was filed with the patent office on 2005-04-28 for pre-warming portions of an inkjet printhead.
Invention is credited to Brenner, James M., Juve, Ronald A., Quintana, Jason.
Application Number | 20050088474 10/691311 |
Document ID | / |
Family ID | 33477249 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050088474 |
Kind Code |
A1 |
Juve, Ronald A. ; et
al. |
April 28, 2005 |
Pre-warming portions of an inkjet printhead
Abstract
An embodiment of a printing system is provided with an inkjet
printhead having plural portions each having an ink-ejecting
nozzle. The printing system includes plural heater elements each
associated with one of the plural portions to pre-warm ink
dispensed by the nozzle of the associated portion in response to a
pre-warming signal. The printing system also includes a controller
configured to generate the pre-warming signal for one or more
heater elements based on a selection criteria for generating the
pre-warming signal only when the nozzle of said associated portion
is required to eject ink during an upcoming print swath.
Inventors: |
Juve, Ronald A.; (Brush
Prairie, WA) ; Brenner, James M.; (Vancouver, WA)
; Quintana, Jason; (Brush Prairie, WA) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD
INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
33477249 |
Appl. No.: |
10/691311 |
Filed: |
October 22, 2003 |
Current U.S.
Class: |
347/17 |
Current CPC
Class: |
B41J 2/04528 20130101;
B41J 2/04563 20130101; B41J 2/0458 20130101 |
Class at
Publication: |
347/017 |
International
Class: |
B41J 029/38 |
Claims
1. A printing system, comprising: an inkjet printhead having plural
portions each having an ink-ejecting nozzle; plural heater elements
each associated with one of said plural portions to pre-warm ink
dispensed by the nozzle of said associated portion in response to a
pre-warming signal; and a controller configured to generate the
pre-warming signal for one or more heater elements based on a
selection criteria for generating the pre-warming signal only when
the nozzle of said associated portion is required to eject ink
during an upcoming print swath.
2. The printing system of claim 1, wherein: each of said plural
portions is configured to dispense a different color of ink; and
the controller is configured to analyze which of said different
colors of ink is required for the upcoming print swath.
3. The printing system of claim 1, wherein the selection criteria
is based upon the type of media to receive ink dispensed from the
printhead.
4. The printing system of claim 3, wherein: one of said plural
portions is configured to dispense ink of a first color having a
first dye load; another of said plural portions is configured to
dispense ink of the first color having a second dye load less than
said first dye load; said controller is configured to interpret
information to determine the type of media to receive ink dispensed
from the printhead; and when a first type of media is determined,
said one of said plural portions is selected for printing and not
said another of said plural portions.
5. The printing system of claim 4, wherein said first type of media
comprises one of plain paper and transparency media.
6. The printing system of claim 1, wherein the selection criteria
is based upon a desired print quality of a resulting image formed
by ink ejection of selected nozzles.
7. The printing system of claim 6, wherein: a first selection
provides a first print quality, and a second selection provides a
second print quality less than said first print quality; one of
said plural portions is configured to dispense ink of a first color
having a first dye load, and another of said plural portions is
configured to dispense ink of the first color having a second dye
load less than said first dye load; each portion comprises two
groups of nozzles which dispense a single color of ink; when
printing under the first selection, ink is dispensed from both of
said one and said another of said plural portions and from said two
groups of nozzles thereof; and when printing under the second
selection, ink is dispensed from only one of said two groups of
nozzles per portion of the printhead.
8. A printing system, comprising: a printhead having plural
portions each having an ink-ejecting nozzle located therein; plural
temperature sensors each associated with one of said plural
portions to monitor the temperature thereof; plural heating
elements, each associated with one of said plural portions to apply
heat thereto in response to a pre-warming signal; and a controller
configured to generate separate pre-warming signals for each of the
plural heating elements in response to the plural temperature
sensors to elevate the temperature of at least one of said plural
portions to a pre-warming temperature.
9. The printing system of claim 8, wherein the controller is
configured to omit generation of a pre-warming signal for another
of said plural portions to produce no pre-warming thereof.
10. The printing system of claim 8, wherein the controller is
configured to cease to generate pre-warming signals upon beginning
printing.
11. The printing system of claim 8, wherein: the controller is
configured to continue to generate pre-warming signals after
printing has begun; the plural temperature sensors are configured
to continue to monitor printing temperature after printing has
begun; and when a printing temperature exceeds the pre-warming
temperature, the controller is configured to cease to generate
pre-warming signals.
12. The printing system of claim 8, wherein: the controller is
configured to analyze which plural portions are required to eject
ink during an upcoming print swath; the controller is configured to
continue to generate pre-warming signals after printing of said
upcoming print swath has begun; and after ink ejection from one of
said plural portions is not required to complete said upcoming
print swath, the controller is configured to cease to generate a
pre-warming signal therefore.
13. A method of pre-warming a multi-color inkjet printhead having
plural portions dispensing ink, including first and second
portions, comprising: generating a pre-warming signal for said
first portion; pre-warming said first portion in response to the
first pre-warming signal; and omitting generation of a pre-warming
signal for said second portion to produce no pre-warming
thereof.
14. The method of claim 13, further comprising: analyzing an
upcoming print swath; determining from said analyzing which of said
plural portions are a dispensing portion required to dispense ink,
and which of said plural portions are a non-dispensing portion not
required to dispense ink during printing of said upcoming print
swath; wherein said first plural portion to receive the pre-warming
signal comprises the dispensing portion; and wherein said second
portion to receive no pre-warming signal comprises the
non-dispensing portion.
15. The method of claim 13, further comprising: determining a type
of media upon which an image is to be printed; and in response to
said determining, selecting which of said plural portions are a
dispensing portion required to dispense ink, and which of said
plural portions are a non-dispensing portion not required to
dispense ink during printing upon said determined type of media;
supplying the pre-warming signal to dispensing portions, and
wherein said omitting comprises omitting generation of a
pre-warming signal for the non-dispensing portions.
16. The method of claim 13, further comprising: monitoring the
temperature of each of said plural portions; and wherein said
generating of said pre-warming signal and said omitting generation
of a pre-warming signal are conducted in response to said
monitoring.
17. The method of claim 13, further comprising: determining a print
quality for printing an upcoming image; in response to said
determining, selecting which of said plural portions are a
dispensing portion required to dispense ink, and which of said
plural portions are a non-dispensing portion not required to
dispense ink during printing of said upcoming image; supplying the
pre-warming signal to dispensing portions; and wherein said
omitting comprises omitting generation of a pre-warming signal for
the non-dispensing portions.
18. The method of claim 13, further comprising: beginning printing
of a print swath; and ceasing generation of the pre-warming signal
upon said beginning.
19. The method of claim 13, further comprising: printing a print
swath from a beginning point to an ending point; continuing
generation of the pre-warming signal after printing from the
beginning point; monitoring printing temperature of each of said
plural portions during said printing; and ceasing to generate the
pre-warming signal when the printing temperature exceeds a
threshold temperature before printing to the ending point.
20. The method of claim 13, further comprising: analyzing an
upcoming print swath; determining from said analyzing which of said
plural portions are transitional portions required to dispense ink
over an initial segment of said upcoming print swath, and not
required to dispense ink over a final segment of said upcoming
print swath; and from said determining, continuing generation of
the pre-warming signal for said transitional portions during
printing of the initial segment and ceasing generation of the
pre-warming signal during printing of the final segment.
21. A printing system, comprising: means for ejecting ink from
plural portions of an inkjet printhead; means for heating each of
said plural portions in response to a pre-warming signal; means for
generating the pre-warming signal for one of said plural portions;
and means for omitting generation of the pre-warming signal for
another of said plural portions.
22. The printing system of claim 21, further comprising: means for
monitoring the temperature of each of said plural portions; and in
response to said means for monitoring, operating said means for
generating the pre-warming signal.
23. The printing system of claim 21, further comprising: means for
analyzing an upcoming print swath; means for sorting which of said
plural portions comprise printing portions and which of said plural
portions comprise non-printing portions of said upcoming print
swath; and means for delivering the pre-warming signal to the
printing portions.
24. The printing system of claim 21, further comprising: means for
determining a type of an upcoming media; means for sorting which of
said plural portions comprise printing portions and which of said
plural portions comprise non-printing portions when printing upon
said upcoming media type; and means for delivering the pre-warming
signal to the printing portions.
25. The printing system of claim 21, further comprising: means for
determining a print quality of an upcoming image to be printed;
means for sorting which of said plural portions comprise printing
portions and which of said plural portions comprise non-printing
portions when printing said upcoming image with the determined
print quality; and means for delivering the pre-warming signal to
the printing portions.
26. The printing system of claim 21, further comprising: means for
monitoring the printing temperature of each of said plural portions
during printing of a print swath; means for determining when a
pre-warming temperature generated by said means for heating is
exceeded by the printing temperature; and means for ceasing to
generate the pre-warming signal when the printing temperature
exceeds the pre-warming temperature.
27. The printing system of claim 21, further comprising: means for
determining when said one of said plural portions is required to
print during an initial segment of a print swath and is not
required to print during a final segment of the print swath; and
means for ceasing generation of the pre-warming signal after
printing said initial segment.
28. An ink dispensing apparatus, comprising: a printhead having
plural portions including first and second portions; plural
ink-ejecting nozzles at least one of which is located in said first
portion, and at least one other of which is located in said second
portion; plural heater elements comprising a first element
associated with said first portion, and a second element associated
with said second portion; wherein the first element is configured
to pre-warm ink dispensed by nozzles of said first portion in
response to a pre-warming signal; and wherein the second element is
configured to fail to pre-warm ink dispensed by nozzles of said
second portion when no pre-warming signal is received.
29. The ink dispensing apparatus claim 28, further comprising
plural temperature sensors each associated with the least one of
said plural portions and configured to monitor the temperature
thereof.
30. The ink dispensing apparatus of claim 29, wherein said plural
temperature sensors are each configured to generate a temperature
signal for use in generating the pre-warming signal.
Description
BACKGROUND
[0001] Inkjet printheads typically move across print media, such as
paper, one swath at a time while selectively ejecting ink droplets
from nozzles to form a desired image. For thermal inkjet printheads
prior to beginning each swath, ink in ejection chambers associated
with each nozzle is pre-warmed to a uniform temperature in earlier
designs for both monochrome and multi-color ejecting printheads.
When printing only one or a few colors from a multi-color
printhead, excess energy is used to pre-warm the ink of colors
which are not used during the swath. Unnecessary heat applied to
the printhead may cause premature aging, reducing printhead
lifetime, as well as consuming additional power unnecessarily
increasing operating and manufacturing costs in terms of oversized
power supplies.
SUMMARY
[0002] An embodiment of a printing system is provided with an
inkjet printhead having plural portions each having an ink-ejecting
nozzle. The printing system includes plural heater elements each
associated with one of the plural portions to pre-warm ink
dispensed by the nozzle of the associated portion in response to a
pre-warming signal. The printing system also includes a controller
configured to generate the pre-warming signal for one or more
heater elements based on a selection criteria for generating the
pre-warming signal only when the nozzle of said associated portion
is required to eject ink during an upcoming print swath.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The present invention can be further understood by reference
to the following description and attached drawings that illustrate
the preferred embodiment(s). Other features and advantages will be
apparent from the following detailed description of the preferred
embodiment(s), taken in conjunction with the accompanying drawings,
which illustrate, by way of example, the principles of the
invention.
[0004] FIG. 1 is a block diagram showing one embodiment of the
present invention.
[0005] FIG. 2 is a flow chart showing one embodiment of the present
invention.
[0006] FIG. 3 is a detailed block diagram of a printing environment
incorporating one embodiment of the present invention.
[0007] FIG. 4 is a flow diagram of one embodiment of a nozzle
member portion of the printing environment of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0008] In the following description, reference is made to the
accompanying drawings, which form a part hereof, and in which is
shown by way of illustration a specific example in which the
invention may be practiced. It is to be understood that other
embodiments may be utilized and structural changes may be made
without departing from the scope of the present invention.
[0009] I. General Overview:
[0010] FIG. 1 is an overview block diagram showing one embodiment
of the printing system 100 constructed in accordance with the
present invention. A user 110 initiates a print request 112 which
may be received by a print analyzer 114 portion of a controller
116. The print analyzer 114 may be activated in response to request
112 for among other purposes monitoring the data sent to an inkjet
printing mechanism, here referred to as printer 118, although other
printing mechanisms may employ the concepts described herein, such
as plotters, photographic printers, facsimile machines, etc. In one
embodiment, the controller 116 is comprised of software, often
referred to as a "printer driver" that resides on a computer system
(not shown) that is accessible to the user 110 and in communication
with printer 118. In alternative embodiments, portions of the
controller 116 may be incorporated in software, firmware and/or
hardware of printer 118 and/or a computer in communication with the
printer.
[0011] The print request 112 may be comprised of print commands and
print data associated with a print job to produce a desired image
on a print media 120, such as paper, transparencies, fabric, etc.
The controller 116 may include a color analyzer system 122 which
receives data from the print analyzer 114 and separates it into
discrete color modules for each page and/or swath of a print job.
The analyzed print data may include command object code that
represents color as well as color intensity, which are then
assigned electronic codes by a color converting system 130 of
controller 116.
[0012] The color coded information from converting system 130 may
then be sent as input data to a printhead assembly 124 of printer
118. A pre-warming or trickle warming system 126 operates to
pre-warm ink prior to the beginning of each print swath, such as by
sending low power current pulses to firing resistors associated
with ink-ejecting nozzles of a nozzle array system 128, although a
separate series of separate pre-warming resistors may be used in
some implementations. These pre-warming current pulses are at a
lower level of power than firing pulses used to eject ink from the
printhead nozzles. The printhead may also include one or more
temperature sensing resistors (TSR's) used to provide feedback to
controller 116 as to the current temperature of the printhead.
[0013] The trickle warming system 126 may include power field
effect transistors (FET's) and provide the capability to warm the
printhead 124 to any desired temperature before and during the
printing operation. The pre-warming process is often referred to as
"trickle warming" because the printhead allows a trickle of energy
to flow through the warming device. The temperature of printhead
assembly 124 rises until the desired temperature is reached and the
warming devices may then be shut off or held at a controlled
warming level.
[0014] The warming devices may be activated by the color analyzer
system 122 according to the need to print a particular color or
colors. In one embodiment, the warming devices may be divided into
color coded sections that lie as close as possible to the
associated resistors of the nozzle array system 128, and may be
back-to-back MOSFET transistors. The firing resistors associated
with the warming devices may be switched on by the combination of
the firing of the address decode, address and data decodes, and the
"and" block and the level shifter. Further, the determination of
whether a nozzle has been selected as a data receiver may be based
on whether the address in the primitive matches the address of the
nozzle transistor and trickle warmer 126. In one embodiment, the
nozzles, the resistors and the warming devices associated with a
particular color may be arranged in columns or substantially linear
arrays on the printhead 124, so that the trickle warmer 126 when
activated only warms that section of the printhead die associated
with the color that is required. This reduces the amount of energy
that is consumed from that required if all columns were warmed
using earlier systems.
[0015] For example, for a tri-color inkjet printhead ejecting cyan,
yellow and magenta colored inks, six nozzle columns may be
provided, typically with two columns for each color arranged
side-by-side in parallel pairs. In the past, prior to printing a
swath the nozzles of all six columns were preheated to a
pre-warming temperature, whether or not all of the colors were to
be used in the upcoming swath. Instead, with the present partial
printhead pre-warming system, if only cyan ink is needed during the
next print swath, then the yellow and magenta inks are not
preheated. Similarly, if a green color is required for the next
print swath, only the cyan and yellow inks are preheated, not the
magenta ink. Pre-warming nozzles which were not used was a waste of
power, and required power supplies to be designed to handle full
power warming for each and every swath. Use of the partial
printhead pre-warming system described herein, where only the
colors or nozzle columns which are to be used in an upcoming swath
are pre-warmed, saves on pre-warming power expended for some
swaths, reducing average power needed for the printhead and thus
allowing optimization in power supply design.
[0016] II. Operation of the Printing System:
[0017] FIG. 2 is a flow chart showing one embodiment of a method
200 of operating the system of FIG. 1 where in a first operation
210 a user decides to print a document or other image with a print
job. In response to operation 210, in a second operation 212, the
printer driver user interface may be accessed by the user to define
input criteria of the print job. Operation 212 may be accomplished
in any suitable manner, such as accessing a user interface of the
printer driver after an application programming interface or dialog
box is initiated and a printer is selected from the dialog box. The
input criteria may include media size, media type, color, etc. The
input criteria may include the type of print quality, often labeled
as "draft," "normal," or "best," which in some implementations may
be input through a keypad on printer 118. Alternatively, default
print criteria may be used without the user needing to make any
special choices.
[0018] In a third operation 214, the application program may
generate print data and drawing commands, which may then be passed
to the printer driver. In a fourth operation 216, the printer
driver may analyze the print data on a specific page to develop
information about the page content, such as intensity and color
information. In operation 216, the printer driver may also then
categorize the print data according to pre-specified categorization
criteria, categorize the print data according to color type,
intensity and location for each swath. Classification of the
document or image may be predefined and set up by the
administrator, which includes a breakdown of the print data into
object types, such as image size, image color, image color depth,
etc., as well as information that may be used to differentiate
between clip-art images and photographic images. For example, a
print job containing two images, one being black text and the other
a color photographic image or business graph, may be analyzed by
the print analyzer 114 and color analyzer 122 by operations 214 and
216 to generate images having, for instance, respective sizes of 10
by 50 pixels (black) and 30 by 100 pixels (color).
[0019] In a fifth operation 218, a determination may be made as to
whether all colors ejected by a multi-color printhead are required
to be printed on an upcoming swath. If so, a YES signal is sent to
a sixth operation 220 where the trickle warming system 126 turns on
the warming elements for all colors. If in the determination
operation 218 it is determined that less than all of the colors are
required for the upcoming swath, a NO signal is issued to a seventh
operation 222, as an alternative to a sixth operation 220. In
operation 222, an identification is made of which colors of the
multi-colored printhead are required to print the upcoming
swath.
[0020] Following the color identification operation 222, in an
eighth operation 224, the trickle warming system 126 turns on the
warming elements for only the colors identified in operation 222,
leaving the warming elements for colors which are not used in the
upcoming swath deactivated. In a ninth operation 226, a summation
is made of the decisions for the colors identified (fewer than all
on the multi-colored printhead), based on selection criteria 228,
such as one or more of the criteria listed in Table 1, below. In a
tenth operation 230, printing the upcoming swath is performed.
1TABLE 1 Selection Criteria for Controlling Pre-Warming of
Printhead Portions Selection Criteria 228 Pre-Warming? Color Based
Only colors used in upcoming swath Media Based Only certain dye
loads of colors Print Quality Based (a) Only certain dye loads of
colors, or (b) Only certain nozzle columns Mid-Swath Based Stop if
nozzles not needed in swath Beginning of Printing Stop after swath
starts Temperature Based Stop if printing maintains temperature
[0021] A system for controlled pre-warming of only a portion(s) of
an inkjet printhead prior to printing based upon one or more
selection criteria, such as those listed by way of example in Table
1 is described in greater detail below, but first, a brief overview
of the criteria examples is presented. The first embodiment uses a
color based selection criteria, where only the colors of ink in the
upcoming swath are pre-warmed. The second embodiment uses a media
based selection criteria, with the type of media being used to
determine which dye loads of colors are pre-warmed. The third
embodiment uses a print quality based selection criteria, where the
print quality (e.g., best, normal or draft) is used to determine
which (a) dye loads of colors or (b) nozzle columns are pre-warmed.
The fourth embodiment uses a mid-swath based selection criteria,
were nozzles which are used initially during a print swath and
later no longer needed, have pre-warming ceased at the point where
they are no longer required. The term "mid-swath" may be a slight
misnomer, but to clarify, this turn off point need not be at the
middle of the swath, but somewhere between the beginning and end of
the swath sometime after the nozzles are no longer required. The
fifth embodiment uses a beginning of printing based selection
criteria, where the pre-warming is stopped after printing has
begun. The sixth embodiment uses a temperature based selection
criteria, where pre-warming is stopped during a print swath when
nozzle firing is capable of maintaining portions of the printhead
at the desired pre-warming temperature. This temperature based
selection criteria system facilitates independent temperature
control of portions of the printhead during a print swath.
[0022] Depending upon which selection criteria 228 are used to
control the pre-warming of a portion(s) of printhead 124, the
decisions of the criteria used may be combined in the summation
action 226 for the colors initially identified in action 222. For
instance, media based and mid-swath based selection criteria may be
combined to initially pre-warm only certain dye loads of colors
before beginning a print swath, with pre-warming stopping during
the swath for nozzles which are no longer needed to conclude the
swath. Another selection criteria may also be added to the media
based and mid-swath based selection criteria, such as the
temperature based selection criteria which causes the pre-warming
to stop if the printing process maintains the pre-warming
temperature while the nozzle(s) is still in use. As another example
of combining selection criteria, the color based and beginning of
printing selection criteria may be combined to only pre-warm ink of
colors used in the upcoming swath, then pre-warming stops after
printing of the swath starts. It is apparent that other
combinations of selection criteria may be made, or the criteria may
be used independently.
[0023] III. Printing System:
[0024] FIG. 3 shows a detailed block diagram of a printing system
300 incorporating one embodiment of the present invention; however
the invention may be incorporated in any multi-color or
multi-nozzle printhead and/or printer configuration. Referring to
FIGS. 1 and 2 along with FIG. 3, the printing system 300 includes a
controller 310 and printhead 124, which is in fluid communication
with an inkjet ink supply 320. The controller 310 and the printer
118, as well as printhead assembly 124, may receive power from an
internal and/or external power supply 330. The controller 310 may
include a data processor 336 that may include several components
discussed further below.
[0025] The printhead 124 may include a firing controller 340 which
receives firing and pre-warming energy from an energy controller
350. The printhead 124 also includes a nozzle member 360,
illustrated in block form as including the first through final
nozzles 362, which forms a portion of a warming system 364. The
warming system 364 may be electrically coupled to the firing
controller 340, which receives activation signals from the data
processor 336 to initiate trickle warming. The nozzle member 360
also includes temperature sensors 366, which may be temperature
sensing resistors (TSR's). As used in the drawing figures, the
designation "1-n" indicates a complete series of items, with "1"
representing the first item of the series, the hyphen denoting the
word "through," and the final item being represented by the
variable "n." The printhead may also include a memory portion 368,
although alternatively, some or all of the memory portion 368 may
be provided as a portion of controller 310.
[0026] The data processor 336 forwards data for a page to be
printed to the memory 368 following analysis by a data analyzer 370
portion of data processor 336. The data analyzer 370 analyzes the
print data swath by swath, looking at which colors 372 are to be
printed, which columns of printhead nozzles 374 are to be used, as
well as the required pre-warming temperature for those colors 372
and nozzles 374 which will be used. According to operation 218
(FIG. 2), the data analyzer 370 determines whether all colors are
to be printed in an upcoming swath, or whether less than the total
number of colors 372 are to be printed on a swath. The
determination of colors 372 may lead the data analyzer 370 to
determine which of columns 374 will be activated, as specific
colors are associated with specific addresses on the warming system
364 on the printhead 124. Having the addresses in close proximity
on the printhead 124 means that less power may be required to warm
adjacent columns on the nozzle member 360.
[0027] For example, for a tri-color inkjet printhead ejecting cyan,
yellow and magenta colored inks, six nozzle columns may be
provided, typically with two columns for each color arranged
side-by-side in parallel pairs. By locating the two nozzle columns
for a given color beside one another, a localized heating effect is
achieved as residual heat is shared between the two columns. Use of
the partial or localized printhead pre-warming system described
herein further aids in saving energy, reducing average power needed
for the printhead and thus allowing optimization in power supply
design.
[0028] The data analyzer 370 may also include a temperature
feedback system 376 configured to receive information from the
temperature sensors 366 on the nozzle member 360 regarding the
operating temperature of the printhead. If the temperature is below
a threshold for those nozzles 362 to be engaged in printing the
upcoming swath, the data analyzer 370 sends an activation signal
through the energy controller 350 system to the firing controller
340. This pre-warming activation signal may be coupled to the color
372 addresses identified above, for the same printed page. The
energy required to effect the warming of columns is efficiently
maintained without compromising the flexibility of the operation to
print a variety of printed pages.
[0029] In one embodiment, the data processor 336 dynamically
formulates decisions to perform firing and timing operations based
on the sensed print data from the color analyzer 122 and color
converting system 130, and gives operating information for
regulating the temperature of, and the energy delivered to, the
printhead 124. These dynamically formulated decisions of data
processor 336 may be based on, among other things, sensed
temperatures of printhead 124, sensed amount of power supplied,
real time tests, and pre-programmed known optimal operating ranges
such as temperature ranges, energy ranges, scan axis directionality
errors, etc. As a result, the data processor 336 enables efficient
operation of the printhead 124 and produces droplets of ink in a
desired pattern with a minimum energy consumption. As mentioned
above with respect to controller 116, the various controller
components, such as data processor 336, data analyzer 370,
temperature controller 376, color analyzer 122 and color converting
system 130, may be programming modules within controller 310,
configured as an application specific integrated circuit (ASIC). In
other embodiments, some of the components of controller 310 may be
comprised of software, often referred to as a "printer driver"
which resides on a computer system (not shown) in communication
with printer 118. In alternative embodiments, portions of the
controller 310 may be incorporated in software, firmware and/or
hardware of printer 118 and/or a computer in communication with the
printer.
[0030] IV. Component Details:
[0031] FIG. 4 shows a detailed block diagram 400 of one embodiment
of portions of the system of FIG. 3, including the nozzles 362 of
nozzle member 360. Referring to FIG. 3 along with FIG. 4, in
general the nozzles 362 may be organized into columns 410 by colors
412; however other arrangements of nozzles may be used such as
circular or oval patterns, zigzag patterns, etc., and the use of
columns 410 is by way of example only for the purposes of
discussion. The nozzles for a particular color selected from a
range of available colors 412 may be arranged in close proximity;
although other arrangements may be more suitable in other
implementations.
[0032] The trickle warming system 126 (FIG. 1) includes a series of
pre-warming resistors, here illustrated as being firing resistors
414, which are associated with ink ejecting nozzles 362 (FIG. 3).
An integrated circuit chip, which may be in the data analyzer 370,
may provide the resistors 414 with operational electrical signals,
such as firing signals for ejecting ink droplets, pre-warming
pulses having energy values lower than those of the firing signals
to pre-warm the ink prior to beginning a swath. Pre-warming the ink
to an optimal temperature produces droplets which are placed more
accurately on the print media and therefore improve the quality of
the printed output on media 120.
[0033] In one embodiment, the ideal temperature for ejecting a
droplet varies with the color of the ink being ejected from a
multi-color printhead. For example, one four-color printhead design
ejects cyan, magenta, yellow and black colored inks. In this
embodiment, the ideal ejection temperature for black ink is
40.degree. C. (Celsius) and 45.degree. C. for colored ink. Below
these temperatures, the ink drop weight is lower than that required
for an ideal ink droplet. If the temperature rises over 50.degree.
C., the risk of nozzle choking through bubble formation becomes a
real possibility, which in an extreme case may cause the heating
element to overheat, for instance, in the illustrated embodiment to
a potentially damaging temperature of 500.degree. C. in three
microseconds. Thus, a temperature monitoring control system
including sensors 336 (FIG. 3) may be exercised to keep
temperatures within working limits.
[0034] To achieve this printhead temperature control, in one
embodiment of the present invention, the controller 310 includes
the temperature feedback system 376 which is configured to monitor
and control the baseline operating temperature of the printhead
124. The temperature feedback system 376 may receive a temperature
indication from a particular sensor (X) 420, which monitors the
temperature of a specific section of the printhead substrate, for
instance a section or region where nozzles are located ejecting a
specific color (X) 422. If the temperature is below the threshold
baseline pre-warm temperature, the temperature feedback system 376
may activate a heater element array comprising resistors (X) 424
located in the printhead nozzle sector monitored by sensor 420 for
nozzles needing pre-warming. In FIG. 4, the variable "X" used with
resistors 424, color 422 and sensor 420 indicates that these are
all mutually associated items, with resistors X 424 being used to
pre-warm the ink of color X 422 ejected by one or more nozzles 1-n
362, with the temperature in the region of these associated nozzles
being monitored by sensor X 420. As mentioned above, in some
implementations, rather than dedicating a temperature sensor to
each firing resistor, a single sensor X 420 may be used to monitor
the temperature associated with several nozzles physically located
near one another in a sector of the printhead. If the temperature
is above a maximum value, the temperature feedback system 376 may
deactivate the heating elements during pre-warming or deactivate
the firing resistors during printing to allow the printhead to cool
to a temperature within acceptable limits.
[0035] Using this dynamic printhead temperature monitoring and
control system 376 allows for other energy conservation schemes.
For example, during printing of a swath, if the temperature of the
firing resistors remains above the target pre-warming temperature
the trickle warming system 126 may be turned off, further
conserving energy. As another example, for a swath beginning in
green and ending in cyan, while only the resistors associated with
the cyan and yellow nozzles are preheated, at the beginning of the
cyan only printing, pre-warming power for the yellow nozzles may be
deactivated, in a mid-swath correction based on the mid-swath
selection criteria 228 listed in Table 1 above.
[0036] As another example, for multi-colored printheads carrying
both full and reduced dye loads of a given color or colors,
typically cyan and magenta, some print jobs may default based on
the type of media used. For instance, plain paper print jobs do not
use the reduced dye loads to avoid saturating the paper, so upon
detecting plain paper, the reduced dye load arrays for cyan and
magenta are not pre-warmed. As a further example, transparencies
typically do not receive the reduced dye loads to avoid bleeding of
one color into another, so again upon detecting a transparency, the
reduced dye load arrays for cyan and magenta are not pre-warmed.
Thus this approach comprises the media based selection criteria 228
listed in Table 1 above, where which nozzles are pre-warmed and
which are not may be selected prior to printing an entire page,
instead of on a swath-by-swath basis. For example, using the media
based selection criteria 228, only full dye loads of ink are
pre-heated for transparencies and plain paper, but not reduced dye
loads, while all dye loads are pre-warmed for photographic and
premium papers.
[0037] The print quality based selection criteria 228 of Table 1
for pre-warming nozzles is another example of a cost saving
technique for pre-warming only a portion or portions of the
printhead. As mentioned above, examples of typical print quality
selections are "best," "normal" and "draft," which may be selected
through the printer driver or often using an input keypad located
on the exterior of the printing mechanism. While the "best" print
mode typically uses all of the nozzles, the "normal" mode may
exclude reduced dye base colors, and the "draft" mode may use only
one column of a pair for a given color. The print quality based
selection criteria 228 is another example of a pre-warming decision
which may be made on an entire page (or print job) basis, rather
than on a swath-by-swath basis, similar to the media based
selection criteria 228 discussed above.
[0038] Use of the color based selection criteria 228 of Table 1
produces significant power savings, particularly when printing
black text from a six color printhead, such as one caring full dye
loads of black, cyan, yellow and magenta inks, along with reduced
dye loads of cyan and magenta inks. Using earlier methods of
pre-warming, all of the nozzles consumed 30 watts of power, as
compared to pre-warming the black ink only, which consumes only 18
watts of power, which is a 40% power savings, a result particularly
important to consumers printing mostly with black, such as for
text. Moreover, the reduced average power needed for the printhead
allows optimization of the power supply, reducing raw material
costs needed to build the printer, resulting in a more economical
product for consumers.
V. Conclusion
[0039] Thus, a system for pre-warming only a portion(s) of an
inkjet printhead prior to printing a swath has been presented with
respect to several illustrated embodiments. One embodiment uses a
color based selection criteria, where only the colors of ink in the
upcoming swath are pre-warmed. Another embodiment uses a media
based selection criteria, with the type of media determines which
dye loads of colors are pre-warmed. Another embodiment uses a print
quality based selection criteria, where the print quality (e.g.,
best, normal or draft) is used to determine which dye loads of
colors or nozzle columns are pre-warmed. Another embodiment uses a
mid-swath based selection criteria, were nozzles which are used
initially during a print swath and later no longer needed, have
pre-warming ceased at the point where they are no longer required.
The term "mid-swath" may be a slight misnomer, but to clarify, this
turn off point need not be at the middle of the swath, but
somewhere between the beginning and end of the swath sometime after
the nozzles are no longer required. Another embodiment uses a
beginning of printing based selection criteria, where the
pre-warming is stopped after printing has begun. Another embodiment
uses a temperature based selection criteria, where pre-warming is
stopped during a print swath when nozzle firing is capable of
maintaining portions of the printhead at the desired pre-warming
temperature. This temperature based selection criteria system
facilitates independent temperature control of portions of the
printhead during a print swath.
[0040] In conclusion, with the system and method of the present
invention, an efficient and proactive printhead 124 is established
through the temperature sensor feedback and control system 366, 376
and pre-warming system 364. This system maintains the relevant
sections of the printhead at an optimum temperature before the
heating energy is transferred to the firing resistors for producing
droplets from multi-color inkjet printheads. A net effect of this
system is that high quality ink droplets are produced at a reduced
energy cost, as well as providing a more economical inkjet printing
mechanism by optimizing power source design.
[0041] The foregoing has described the principles, preferred
embodiments and modes of operation of the present invention.
However, the invention should not be construed as being limited to
the particular embodiments discussed. The above-described
embodiments should be regarded as illustrative rather than
restrictive, and it should be appreciated that variations may be
made in those embodiments by workers skilled in the art without
departing from the scope of the present invention as defined by the
following claims.
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